[11C] Carbon monoxide has been used in the palladium-mediated synthesis of [carbonyl- 11C] ketones. Methyl iodide, vinylic and arylic halides and trifluoromethanesulfonates (triflates) have been coupled with tin reagents with insertion of [11C] carbon monoxide at very low concentrations (10–100 nmol [11C] CO in a total volume of 10 ml). The labelled products are obtained in 36–62% isolated decay-corrected radiochemical yields within 30 ...